Minimally invasive surgical techniques are known for performing medical procedures within the cardiovascular system, and a number of medical conditions may be treated using ablative techniques and devices. For example, cryoablation, or the removal of heat from body tissue to “stun” or kill the tissue cells, is one technique that has proven effective in the treatment of many kinds of cardiac arrhythmias.
One such arrhythmia, atrial fibrillation, is a medical condition resulting from abnormal electrical activity within the heart. This abnormal activity may occur at regions of the heart including the sino-atrial (SA) node, the atrioventricular (AV) node, the bundle of His, or within other areas of cardiac tissue. Moreover, atrial fibrillation may be caused by abnormal activity within an isolated focal center within the heart. These foci can originate within a pulmonary vein, and particularly the superior pulmonary veins. Atrial fibrillation may be treatable by ablation of the abnormal tissue within the left atrium and/or the pulmonary vein. In particular, minimally invasive techniques, such as those described above, use ablation catheters to target the pulmonary vein in order to ablate any identified foci having abnormal electrical activity.
A procedure called pulmonary vein isolation (PVI) is commonly used to treat atrial fibrillation. This procedure involves the use of a cryogenic device, which is generally positioned at the ostium of a pulmonary vein (PV) such that any blood flow exiting the PV into the left atrium (LA) is completely blocked. At this position the cooling of the balloon system may be activated for a sufficient duration to create a desired lesion at the PV-LA junction. If a cryoballoon is used as the treatment element of the cryogenic device, the balloon is typically inflated using a fluid coolant, enabling the balloon to create a lesion about the ostium and/or antrum of the PV to disrupt aberrant electrical signals exiting the PV. However, although this method may be effective in treating atrial fibrillation in the short term, recent studies indicate that long-term success ranges from about 70% to about 80%.
A newer method of treating atrial fibrillation is called PV antrum radial-linear (PAR) ablation, and research indicates that this method may be more effective than PVI. Instead of creating a circumferential lesion about the PV ostium and/or antrum as in PVI, the PAR ablation technique involves the creation of one or more linear lesions in different radial directions from one or more PV ostia into the PV/left atrium (LA) junction. To create linear lesions of a sufficient depth to disrupt the aberrant electrical signals, however, the treatment element of an ablation device such as a focal catheter may have to be repeatedly traced over the linear lesions. This can be a time-consuming process and user error may lead to non-linear lesions and ablation of non-target tissue.
In view of the above, it is desirable to provide for an ablation device that can be used to quickly and easily perform a PAR ablation procedure in the treatment of, for example, atrial fibrillation.